1. Field of the Invention
The present invention relates to a lubricated joint and method of assembly, and more particularly to joint assemblies in which the lubricant which contacts the joint assembly is contained under pressure by an expanded boot.
2. Description of the prior art.
The following patents illustrate various means for protecting and lubricating universal joints: U.S. Pat. Nos. 1,433,130; 2,755,643; 1,922,431; 2,869,342; 2,097,424; 3,423,959.
3. Summary of the invention.
Two seemingly unrelated problems with prior art lubricated joint assemblies are solved with the present invention. One problem frequently encountered is that the lubricant cover or boot does not adequately protect the lubricant from the atmosphere and accordingly the lubricant tends to gel and harden over prolonged periods of time. Another problem is that the manufacturer of the lubricated joint assembly must maintain a large inventory of boot sizes and boot shapes to satisfy the specialized customer requirements.
In the present invention an elastic, air impervious boot is used and the filling of the boot with lubricant is accompanied by a removal of all air from the boot. The lubricant is introduced into the boot with a sufficient pressure above atmospheric pressure to cause the boot to expand and, in seeking to recover from such expansion, compress the lubricant. The result is a pressurized boot which minimizes the opportunity for contact between the lubricant and the atmosphere.
The use of an elastic boot provides the additional advantage that the final size and configuration of the pressurized boot can be determined by the volume of lubricant introduced under pressure to the interior of the boot, and by variations in the wall thickness of the boot.
An object of the present invention is to provide a new and improved lubricated joint assembly.
Another object of the present invention is to provide a new and improved method for lubricating joint assemblies.
A further object of the present invention is to provide an improved means for shaping boots for use in lubricated joint assemblies.
Still another object of the present invention is to provide an improved means for pressurizing lubricated joint assemblies.